__str__ method for ACL's shouldn't fail on empty ones

git-svn-id: http://svn.savannah.nongnu.org/svn/rdiff-backup@873 2b77aa54-bcbc-44c9-a7ec-4f6cf2b41109

trunk/rdiff-backup/rdiff_backup/eas_acls.py

@@ -228,6 +228,7 @@ class AccessControlLists:
 
 	def __str__(self):
 		"""Return text version of acls"""
+		if not self.entry_list: return ""
 		slist = map(self.entrytuple_to_text, self.entry_list)
 		if self.default_entry_list:
 			slist.extend(map(lambda e: "default:" + self.entrytuple_to_text(e),